| 1. |
- Mamontov, Eugen, 1955, et al.
(författare)
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What stochastic mechanics are relevant to the study of living systems?
- 2005
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Ingår i: Proceedings of the Latvian Academy of Sciences. Section B: Natural, Exact and Applied Sciences. - Riga, Latvia : Latvian Academy of Sciences. - 1407-009X. ; 59:6, s. 255-262
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Tidskriftsartikel (refereegranskat)abstract
- Biologists have identified many features of living systems which cannot be studied by application of fundamental statistical mechanics (FSM). The present work focuses on some of these features. By discussing all the basic approaches of FSM, the work formulates the extension of the kinetic-theory paradigm (based on the reduced one-particle distribution function) that possesses all the considered properties of the living systems. This extension appears to be a model within the generalized-kinetic theory developed by N. Bellomo and his co-authors. In connection with this model, the work also stresses some other features necessary for making the model relevant to living systems. An example is discussed, which is a generalized kinetic equation coupled with the probability-density equation which represents the varying component content of a living system. The work also suggests directions for future research.
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| 2. |
- Castleton, Christopher, 1969-, et al.
(författare)
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Managing the supercell approximation for charged defects in semiconductors : Finite-size scaling, charge correction factors, the band-gap problem, and the ab initio dielectric constant
- 2006
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 73:035215, s. 11-
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Tidskriftsartikel (refereegranskat)abstract
- The errors arising in ab initio density functional theory studies of semiconductor point defects using the supercell approximation are analyzed. It is demonstrated that (a) the leading finite size errors are inverse linear and inverse cubic in the supercell size and (b) finite size scaling over a series of supercells gives reliable isolated charged defect formation energies to around +-0.05 eV. The scaled results are used to test three correction methods. The Makov-Payne method is insufficient, but combined with the scaling parameters yields an ab initio dielectric constant of 11.6+-4.1 for InP. Gamma point corrections for defect level dispersion are completely incorrect, even for shallow levels, but realigning the total potential in real-space between defect and bulk cells actually corrects the electrostatic defect-defect interaction errors as well. Isolated defect energies to +-0.1 eV are then obtained using a 64 atom supercell, though this does not improve for larger cells. Finally, finite size scaling of known dopant levels shows how to treat the band gap problem: in < or = 200 atom supercells with no corrections, continuing to consider levels into the theoretical conductin band (extended gap) comes closest to experiment. However, for larger cells or when supercell approximation errors are removed, a scissors scheme stretching the theoretical band gap onto the experimental one is in fact correct.
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| 3. |
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| 4. |
- Nafari, Alexandra, 1980, et al.
(författare)
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MEMS Sensor for in Situ TEM Atomic Force Microscopy
- 2008
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Ingår i: Journal of microelectromechanical systems. - : IEEE Press. - 1057-7157 .- 1941-0158. ; 17:2, s. 328-333
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Tidskriftsartikel (refereegranskat)abstract
- Here, we present a MEMS atomic force microscope sensor for use inside a transmission electron microscope (TEM). This enables direct in situ TEM force measurements in the nanonewton range and thus mechanical characterization of nanosized structures. The main design challenges of the system and sensor are to reach a high sensitivity and to make a compact design that allows the sensor to be fitted in the narrow dimensions of the pole gap inside the TEM. In order to miniaturize the sensing device, an integrated detection with piezoresistive elements arranged in a full Wheatstone bridge was used. Fabrication of the sensor was done using standard micromachining techniques, such as ion implantation, oxide growth and deep reactive ion etch. We also present in situ TEM force measurements on nanotubes, which demonstrate the ability to measure spring constants of nanoscale systems.
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| 5. |
- Piscitelli, Francesco, et al.
(författare)
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Neutron reflectometry on highly absorbing films and its application to (B4C)-B-10-based neutron detectors
- 2016
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Ingår i: Royal Society of London. Proceedings A. Mathematical, Physical and Engineering Sciences. - : The Royal Society. - 1364-5021 .- 1471-2946. ; 472:2185
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Tidskriftsartikel (refereegranskat)abstract
- Neutron reflectometry is a powerful tool used for studies of surfaces and interfaces. The absorption in the typical studied materials is neglected and this technique is limited only to the reflectivity measurement. For strongly absorbing nuclei, the absorption can be directly measured by using the neutron-induced fluorescence technique which exploits the prompt particle emission of absorbing isotopes. This technique is emerging from soft matter and biology where highly absorbing nuclei, in very small quantities, are used as a label for buried layers. Nowadays, the importance of absorbing layers is rapidly increasing, partially because of their application in neutron detection; a field that has become more active also due to the He-3-shortage. We extend the neutron-induced fluorescence technique to the study of layers of highly absorbing materials, in particular (B4C)-B-10. The theory of neutron reflectometry is a commonly studied topic; however, when a strong absorption is present the subtle relationship between the reflection and the absorption of neutrons is not widely known. The theory for a general stack of absorbing layers has been developed and compared to measurements. We also report on the requirements that a (B4C)-B-10 layer must fulfil in order to be employed as a converter in neutron detection.
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| 6. |
- Englund, Oskar, 1982
(författare)
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On Sustainability of Biomass for Energy and the Governance Thereof
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Due to concerns about climate change, energy security, and resource scarcity, non- renewable resources are increasingly being displaced by biomass. As with most human activities, the production of biobased products can be associated with negative impacts. Primarily, this relates to the biomass supply systems, i.e., agriculture and forestry, which currently are major causes of biodiversity loss and degradation of ecosystem services. Developing sustainable production systems when transitioning from non-renewable resources to biomass is imperative. This thesis aims to clarify the meaning of sustainability in the context of biomass for bioenergy, and contribute to our understanding of how different forms of governance can promote sustainably sourced biomass for bioenergy. The thesis is based on five appended papers: Paper I analyses to what extent, where, and under what conditions oil palm for biodiesel in Brazil can be produced profitably, and what risks and opportunities that can be associated with introducing large-scale oil palm production in Brazil. Paper II lays the foundation for understanding how new biomass production can be introduced into landscapes while supporting rather than compromising the ability of the landscape to supply other ecosystem services. Paper III describes different forms of governance and shows how these can play different roles in promoting sustainable bioenergy in different countries. Paper IV focuses on how short rotation coppice production systems are affected by EU policy and how different governance forms can assist in adapting production systems to conform to the corresponding sustainability requirements. Finally, Paper V assesses how sustainability certification (private governance) addresses biodiversity conservation and contributes to our understanding of possible improvements.
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| 7. |
- Magnuson, Martin, et al.
(författare)
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Competition between decay and dissociation of core-excited carbonyl sulfide studied by x-ray scattering
- 1999
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 59:6, s. 4281-4287
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Tidskriftsartikel (refereegranskat)abstract
- We show evidence of dissociation during resonant inelastic soft x-ray scattering Carbon and oxygen K-shell and sulfur L-shell resonant and nonresonant x-ray emission spectra were measured using monochromatic synchrotron radiation for excitation and ionization. After sulfur L-2,L-3-->pi*, sigma* excitation, atomic lines are observed in the emission spectra as a consequence of competition between de-excitation and dissociation. In contrast thr carbon and oxygen spectra show weaker line-shape variations and no atomic Lines. The spectra are compared to results from ab initio calculations. The discussion of the dissociation paths is based on calculated potential energy surfaces and atomic transition energies.
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| 8. |
- Hedenborg, Susanna, et al.
(författare)
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Outdoorification of sports and recreation : a leisure transformation under the COVID-19 pandemic in Sweden
- 2024
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Ingår i: Annals of Leisure Research. - : Informa UK Limited. - 1174-5398 .- 2159-6816. ; 27:1, s. 36-54
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Tidskriftsartikel (refereegranskat)abstract
- Following the outbreak of the COVID-19 pandemic, most European countries imposed lockdowns, whereas Sweden introduced soft restrictions. Sports and physical activity could continue if conducted 'safely' and outdoor activities were even promoted if restrictions on the number of participants were not violated. The aim of this article is to demonstrate how the pandemic led to transitions and transformations of typical indoor sports activities to the outdoors and to outdoor recreation, or what we call an outdoorification process of sports and recreation, and how the changes were perceived by the population. Sweden is used as a case study. The inquiry is based on three studies involving more than 100 semi-structured interviews, two national questionnaire surveys and a regional-based PPGIS study. Based on the results, we argue that the outdoorification process is likely to influence how sport and recreation is understood and practiced also in the years after the pandemic.
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| 9. |
- Lidenmark, Cecilia, 1976-, et al.
(författare)
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The adhesive behavior of extracted latex polymers towards silicon oxide and cellulose
- 2013
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Ingår i: International Journal of Adhesion and Adhesives. - : Elsevier. - 0143-7496 .- 1879-0127. ; 44, s. 250-258
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Tidskriftsartikel (refereegranskat)abstract
- The objective with this work is to compare the adhesive behavior for latex polymers of different glass transition temperatures (T-g) at different length scales and with different contact times. This is accomplished by two techniques: AFM colloidal probe force measurements and JKR-measurements. The aim is to compare the results from these two techniques and relate them to the interaction of the latex polymers towards oxidized silicon wafers and silica/cellulose probes. Theory suggests that altering the short timeframes used in the colloidal probe technique does not affect the ranking of the adhesion for the different polymers, but for the macroscopic JKR-technique it influences the measured work of adhesion. It is therefore important to let the system reach a steady state before assuming complete spreading and adhesion. AFM and JKR measurements showed the same trends where the polymer with lowest content of styrene has the lowest T-g and the highest adhesion, due to the larger polymer chain mobility.
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| 10. |
- Reifarth, R., et al.
(författare)
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Nuclear astrophysics with radioactive ions at FAIR
- 2016
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 665:1
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Konferensbidrag (refereegranskat)abstract
- The nucleosynthesis of elements beyond iron is dominated by neutron captures in the s and r processes. However, 32 stable, proton-rich isotopes cannot be formed during those processes, because they are shielded from the s-process flow and r-process beta-decay chains. These nuclei are attributed to the p and rp process. For all those processes, current research in nuclear astrophysics addresses the need for more precise reaction data involving radioactive isotopes. Depending on the particular reaction, direct or inverse kinematics, forward or time-reversed direction are investigated to determine or at least to constrain the desired reaction cross sections. The Facility for Antiproton and Ion Research (FAIR) will offer unique, unprecedented opportunities to investigate many of the important reactions. The high yield of radioactive isotopes, even far away from the valley of stability, allows the investigation of isotopes involved in processes as exotic as the r or rp processes.
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